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Hepatic sinusoidal obstruction syndrome, also known as veno-occlusive disease, can occur as a complication of myeloablative chemotherapy, as a result of low-intensity chemotherapy-related liver toxicity or radiotherapy of the liver. Symptoms of sinusoidal obstruction syndrome can range from asymptomatic to liver dysfunction or severe disease with life-threatening acute multi-organ failure. Imaging features can suggest or support this clinical diagnosis. Familiarity with the imaging spectrum of sinusoidal obstruction syndrome is therefore important for both radiologists and clinical oncologists. Here, multi-modality radiologic appearances of sinusoidal obstruction syndrome in pediatric patients are illustrated, including outcome after follow-up., (© 2021. The Author(s).)

Arterial spin labeling is a noninvasive, non-gadolinium-dependent magnetic resonance imaging (MRI) technique to assess cerebral blood flow. It provides insight into both tissue metabolic activity and vascular supply. Because of its non-sensitivity toward blood-brain barrier leakage, arterial spin labeling is also more accurate in cerebral blood flow quantification than gadolinium-dependent methods. The aim of this pictorial essay is to promote the application of arterial spin labeling in pediatric neuroradiology. The authors provide information on artifacts and pitfalls as well as numerous fields of application based on pediatric cases.

Pediatric chest MRI is challenging. High-resolution scans of the lungs and airways are compromised by long imaging times, low lung proton density and motion. Low signal is a problem of normal lung. Lung abnormalities commonly cause increased signal intenstities. Among the most important factors for a successful MRI is patient cooperation, so the long acquisition times make patient preparation crucial. Children usually have problems with long breath-holds and with the concept of quiet breathing. Young children are even more challenging because of higher cardiac and respiratory rates giving motion blurring. For these reasons, CT has often been preferred over MRI for chest pediatric imaging. Despite its drawbacks, MRI also has advantages over CT, which justifies its further development and clinical use. The most important advantage is the absence of ionizing radiation, which allows frequent scanning for short- and long-term follow-up studies of chronic diseases. Moreover, MRI allows assessment of functional aspects of the chest, such as lung perfusion and ventilation, or airways and diaphragm mechanics. In this review, we describe the most common MRI acquisition techniques on the verge of clinical translation, their problems and the possible solutions to make chest MRI feasible in children.

Background: To study early neurodevelopment in preterm infants, evaluation of brain maturation and injury is increasingly performed using diffusion tensor imaging, for which the reliability of underlying data is paramount., Objective: To review the literature to evaluate acquisition and processing methodology in diffusion tensor imaging studies of preterm infants., Materials and Methods: We searched the Embase, Medline, Web of Science and Cochrane databases for relevant papers published between 2003 and 2013. The following keywords were included in our search: prematurity, neuroimaging, brain, and diffusion tensor imaging., Results: We found 74 diffusion tensor imaging studies in preterm infants meeting our inclusion criteria. There was wide variation in acquisition and processing methodology, and we found incomplete reporting of these settings. Nineteen studies (26%) reported the use of neonatal hardware. Data quality assessment was not reported in 13 (18%) studies. Artefacts-correction and data-exclusion was not reported in 33 (45%) and 18 (24%) studies, respectively. Tensor estimation algorithms were reported in 56 (76%) studies but were often suboptimal., Conclusion: Diffusion tensor imaging acquisition and processing settings are incompletely described in current literature, vary considerably, and frequently do not meet the highest standards.

Background: Cerebral MRI performed on preterm infants at term-equivalent 30 weeks' gestational age (GA) is increasingly performed as part of standard clinical care., Objective: We evaluated safety of these early MRI procedures., Materials and Methods: We retrospectively collected data on patient safety of preterm infants who underwent early MRI scans. Data were collected at fixed times before and after the MRI scan. MRI procedures were carried out according to a comprehensive guideline., Results: A total of 52 infants underwent an MRI scan at 30 weeks' GA. Although no serious adverse events occurred and vital parameters remained stable during the procedure, minor adverse events were encountered in 26 infants (50%). The MRI was terminated in three infants (5.8%) because of respiratory instability. Increased respiratory support within 24 h after the MRI was necessary for 12 infants (23.1%) and was significantly associated with GA, birth weight and the mode of respiratory support. Hypothermia (core temperature < 36°C) occurred in nine infants (17.3%). Temperature dropped significantly after the MRI scan., Conclusion: Minor adverse events after MRI procedures at 30 weeks GA were common and should not be underestimated. A dedicated and comprehensive guideline for MRI procedures in preterm infants is essential.

Background: Bone age (BA) assessment is a routine procedure in paediatric radiology, for which the Greulich and Pyle (GP) atlas is mostly used. There is rater variability, but the advent of automatic BA determination eliminates this., Objective: To validate the BoneXpert method for automatic determination of skeletal maturity of healthy children against manual GP BA ratings., Materials and Methods: Two observers determined GP BA with knowledge of the chronological age (CA). A total of 226 boys with a BA of 3-17 years and 179 girls with a BA of 3-15 years were included in the study. BoneXpert's estimate of GP BA was calibrated to agree on average with the manual ratings based on several studies, including the present study., Results: Seven subjects showed a deviation between manual and automatic BA in excess of 1.9 years. They were re-rated blindly by two raters. After correcting these seven ratings, the root mean square error between manual and automatic rating in the 405 subjects was 0.71 years (range 0.66-0.76 years, 95% CI). BoneXpert's GP BA is on average 0.28 and 0.20 years behind the CA for boys and girls, respectively., Conclusion: BoneXpert is a robust method for automatic determination of BA.

Background: Isolated synostosis of the frontosphenoidal suture is very rare and difficult to diagnose. Little has been reported on the clinical presentation and fetal development of this suture., Objective: To understand the development of the frontosphenoidal suture and the outcome of its synostosis., Materials and Methods: We studied the normal fetal development of the frontosphenoidal suture in dry human skulls and the clinical features of four patients with isolated synostosis of the frontosphenoidal suture., Results: The frontosphenoidal suture develops relatively late during the second trimester of pregnancy, which explains the mild phenotype when there is synostosis. This rare craniosynostosis results in a deformity that causes recession of the lateral part of the frontal bone and supraorbital rim, with minimal facial asymmetry. Three-dimensional CT is the best examination to confirm the diagnosis., Conclusion: Isolated frontosphenoidal synostosis should be considered in patients with unilateral flattening of the forehead at birth that does not improve within the first few months of life.

Background: Ultrasonography (US) as a diagnostic tool in the work-up of boys with nonpalpable testes (NPT) is still controversial., Objective: To evaluate the relation between US and operative findings in boys with NPT., Materials and Methods: During a 7-year period we saw 135 boys with 152 NPT. All were examined by the referring physician or a paediatric surgeon, underwent US examination, and were then re-examined afterwards by a specialist. Finally, all boys were surgically explored for testicular position., Results: US located 103 NPT (68%), 16 within the abdomen and 87 in the inguinal canal. With knowledge of the US result, 37 testes were palpable on re-examination. The sensitivity of US was 97% for inguinal and 48% for abdominal viable testes. Of the 49 testes (32%) missed by US, 16 were viable in either the abdominal (n=14) or the inguinal (n=2) position., Conclusion: All boys with presumed NPT should be referred to a specialist. US is useful to determine localization of NPT, which facilitates planning the surgical procedure. An inguinal exploration is called for when US identifies the testis in the inguinal canal. Because the sensitivity of US for viable abdominal testes is only 48%, we now always perform laparoscopic exploration when US is negative.

Background: In recent years interest in bone densitometry in children has increased., Objective: To evaluate the clinical application of digital X-ray radiogrammetry (DXR) and compare the results with those of dual-energy X-ray absorptiometry (DXA)., Materials and Methods: A total of 41 children with acute lymphoblastic leukaemia (ALL) and 26 children with growth hormone deficiency (GHD) were included in this longitudinal study. Radiographs of the left hand were obtained and used for DXR. DXA of the total body and of the lumbar spine was performed., Results: In both study populations significant correlations between DXR and DXA were found, and, with the exception of the correlation between DXR bone mineral density (DXR-BMD) and bone mineral apparent density in the GHD population, all correlations had a P-value of <0.001. During treatment a change in DXR-BMD was found in children with GHD., Conclusions: Our study showed that DXR in a paediatric population shows a strong correlation with DXA of the lumbar spine and total body and that it is able to detect a change in BMD during treatment.

Background: Reducing the dose for each CT scan is important for children with cystic fibrosis (CF)., Objective: To determine whether the number of CT images and therefore the dose per CT scan could be reduced without any significant loss of information in children with CF., Materials and Methods: A cohort of children with CF was followed with biennial surveillance CT scans, obtained in inspiration after a voluntary breath-hold as 1-mm thick images at 10-mm intervals from lung apex to base. A random set of 20 baseline CT scans and 10 follow-up CT scans were blinded. Sets of every image (10-mm intervals), every second image (20-mm intervals), every third image (30-mm intervals) and a selection of three and five images were scored randomly using a published CT scoring system by one experienced observer., Results: The 20 subjects were 10 years of age with a range of 3.7-17.6 years at baseline. Fewer CT images resulted in a significantly lower (less abnormal) CT score and the number of patients positive for abnormalities decreased subsequently. At intervals greater than 20 mm no significant change in CT score over 2 years could be detected, while the CT scores at 10-mm (P=0.02) and 20-mm (P=0.02) intervals worsened significantly., Conclusions: A reduction in the number of inspiratory CT images by increasing the interval between images to greater than 10 mm is not a valid option for radiation dose reduction in children with CF.

We report the CT and MRI findings of congenital bilateral plexiform neurofibromas of the cavernous sinuses in a 2-month-old girl. Contrast-enhanced CT showed enhancement of masses in both cavernous sinuses and enlargement of both superior orbital fissures. On MRI the masses were isointense with muscle on T1-weighted images, hypointense on T2-weighted images and showed strong homogeneous enhancement on contrast-enhanced T1-weighted images. A dural tail sign was observed. The diagnosis was proven by biopsy.

Background: Several longitudinal studies have shown contradictory results regarding the change in bone status in children with acute lymphoblastic leukaemia (ALL) using dual-energy X-ray absorptiometry as the bone assessment technique., Objective: To determine whether a more recently developed bone assessment technique which does not use radiation, tibial ultrasonometry, can be used for the detection of short-term changes., Patients and Methods: From January 1997 to February 2001, 37 patients (25 boys, 12 girls, mean age 9.0 years, range 3.0-16.8 years) were included in a longitudinal study to assess changes in bone status induced by the disease itself and/or treatment. Of these 37 patients, 35 had a measurement at the start of therapy (t0), 26 at 6 months (t6), 24 at 12 months (t12), 11 at 24 months (t24) and 9 at 36 months (t36). For assessment of bone mass, the tibial ultrasound (US) device SoundScan Compact was used, which measures the speed of sound (SOS) along the cortex of the tibia over a fixed length of 5 cm at the mid-tibial point. RESULTS. The SOS standard deviation (SD) scores were significantly lower at t6, t12, t24 and t36 than at baseline (t0). The biggest change was found between t0 and t6. During follow-up, no significant correlation was found between changes from baseline of height SD scores and SOS SD scores, indicating that tibial ultrasonometry was not measuring growth. After ending therapy (t36), no further growth retardation was found., Conclusions: Short-term changes of SOS SD scores in children with ALL can be detected by tibial ultrasonometry. Tibial ultrasonometry measures a change in bone status, not growth.

Background: In our Paediatric Radiology Department, the Greulich and Pyle technique is used to assess skeletal age. Several authors have raised questions with regard to the applicability of this technique in a contemporary paediatric and adolescent population., Objective: To compare skeletal age and calendar age in a healthy Dutch Caucasian population in order to test the applicability in this specific population., Materials and Methods: For this study we enrolled 278 Dutch Caucasian boys (age range 5.0-19.5 years, mean 12.6 years) and 294 Dutch Caucasian girls (age range 5.2-19.9 years, mean 12.2 years). Radiographs of the left hand were scored according to the Greulich and Pyle atlas by two investigators., Results: Intra-observer coefficient of variation of duplicate assessment of skeletal age for investigator 1 (resident) was 2.4 % and for investigator 2 (radiologist) was 1.5 %. We found no significant systematic differences between the two observers regarding variability and levels of measurement, and the agreement was good. There was a strongly significant correlation between skeletal and calendar age rgirls = 0.974 and rboys = 0.979 (P < 0.001). On average, calendar age preceded skeletal age by a small amount (1.7 months in girls and 3.3 months in boys, both P < 0.001)., Conclusions: The reliability of the Greulich and Pyle atlas in our study corresponds well with previously reported studies. Based on our data, we conclude that the Greulich and Pyle atlas is still applicable in Dutch Caucasian children and adolescents.

Objective: To evaluate the significance of thickening of the wall of the renal collecting system by US., Materials and Methods: Wall thickening of the renal collecting system was seen during US in 62 collecting systems of 51 patients over a period of 2 years. The medical and radiological records of these patients were reviewed with special attention to the definitive diagnosis and other clinical and radiological parameters. Moreover, a control group consisting of 48 renal collecting systems was examined to establish normal values for the thickness of the wall of the collecting system., Results: Of the 62 collecting systems (mean wall thickness 1.6 mm, range 0.8-3.1 mm), vesicoureteric reflux (VUR) was present in 18 cases, urinary tract infection (UTI) in 11, and both VUR and UTI in 9 cases. In 10 cases, intermittent dilatation was present caused by primary obstructive megaureter (n = 2), pelvi-ureteric junction stenosis (n = 4), high-pressure bladder (n = 3), or of unknown cause (n = 1). In 11 cases, transient dilatation had been present in the recent past (usually prenatally detected hydronephrosis), but had disappeared at the time of the US examination. In 3 patients, no definite cause for the wall thickening could be established. In the control group, wall thickness ranged from 0.1 to 0.8 mm., Conclusions: The upper limit for wall thickness of the normal collecting system in children is 0.8 mm. Thickening of the wall of more than 0.8 mm should be considered as pathological and is caused by urinary tract infection, intermittent dilatation (e. g., VUR), and dilatation in the recent past.